This paper presents a numerical approach using the discrete element method (DEM) to simulate failure modes of metal skinned sandwich panels subjected to uniform pressure. The panels were modeled by assemblies of small size particles that interact with each other through contacts. Different constitutive laws are introduced for the contacts to represent the stiffness and strength characteristics of the metal panels and the core materials. Parametric studies are conducted first to assess the influence of particle radius and friction coefficient on the numerical predictions. The model is then used to predict the mechanical behavior of four sandwich panels with different geometry. The panels are also tested in the laboratory and the test results are compared with the predictions. The comparisons suggest that the DEM model can be used as an alternative tool to predict stiffness and strength of sandwich composites. Moreover the approach can predict detailed local damage and failure modes, which is an advantage over the conventional numerical methods, such as the finite element method.